An instruction tracing system (ITS) is a tracing capability, which provides a software execution control flow trace. The trace output is in the form of packets of variable sizes. In one example, an ITS architecture includes a periodic decoder synchronization packet, called a boundary packet. The boundary packet is a unique byte pattern in a packet log and hence serves as a sync point for a trace packet decoder (“decoder”). So, the decoder may scan through the packet log to find the boundary packet, at which point it is assured that the next byte after the boundary packet in the packet log is the first byte of a packet. As such, the boundary packet serves as the starting point for packet decode, which causes the decoder to align itself behind the first byte of the packet on packet boundaries before it may begin the packet decode.